This invention relates to energy storage devices and particularly to electrode separators in an energy storage device, such as batteries and capacitors, capable of delivering very high specific power and very high energy density. More particularly, the present invention relates to an aquagel separator utilized between carbon aerogel electrodes, such as used in batteries and electrochemical double-layered capacitors.
Low density organic aerogels have known applications in high energy physics, chemical catalysis and ion exchange reactions. U.S. Pat. Nos. 4,806,290, 4,873,218 and 4,997,804 illustrate the preparation of such aerogels. Recently, electrodes formed from machinable, structurally stable carbon foams derived from the pyrolysis of organic foams have been developed for use in energy storage devices such as batteries, capacitors and double-layer capacitors (supercapacitors) as described and claimed in parent application Ser. No. 07/822,438, now U.S. Pat. No. 5,260,855.
Separators used between electrodes in energy storage devices have been constructed of rubber, plastic, etc. to prevent the conduction of electrons between the electrode, but such prior known separators have had a tendency to dry out or breakdown over a period of time, or exhibit poor ionic conductivity.
The need exists for electrode separators with desirable physical and chemical properties to enhance the energy storage and dissipation from capacitor devices, for example. In particular, a need exists for electrode separators in electrochemical energy storage devices which have ionic conductivity, low cost, good interfacial contact, improved manufacturability, and increased safety.